U.S. patent application number 09/963309 was filed with the patent office on 2002-01-31 for cylinder head gasket.
This patent application is currently assigned to TAIHO KOGYO CO., LTD.. Invention is credited to Goto, Eisaburo, Jinno, Osamu, Kawakita, Tatsuya, Nakamura, Hideo, Omura, Seiji.
Application Number | 20020011709 09/963309 |
Document ID | / |
Family ID | 17400750 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011709 |
Kind Code |
A1 |
Jinno, Osamu ; et
al. |
January 31, 2002 |
Cylinder head gasket
Abstract
A cylinder head gasket includes a pair of first and second
gasket substrates. The gasket substrates are each formed with a
first and a second projection which project in opposite directions,
with a clearance therebetween. According to a first aspect of the
invention, each projection undergoes a plastic deformation toward
the clearance defined between them when the gasket substrates are
held sandwiched between a cylinder head and a cylinder block, each
projection undergoing a magnitude of plastic deformation which is
greater or lesser in accordance with the magnitude of a surface
pressure therebetween. According to a second aspect of the
invention, each projection is formed with a radially central part
which projects toward the radially central part of the other
projection and which is in close contact with each other
continuously in the circumferential direction.
Inventors: |
Jinno, Osamu; (Toyota-shi,
JP) ; Goto, Eisaburo; (Toyota-shi, JP) ;
Omura, Seiji; (Toyota-shi, JP) ; Kawakita,
Tatsuya; (Toyota-shi, JP) ; Nakamura, Hideo;
(Toyota-shi, JP) |
Correspondence
Address: |
Flynn, Thiel, Boutell & Tanis, P.C.
2026 Rambling Road
Kalamazoo
MI
49008-1699
US
|
Assignee: |
TAIHO KOGYO CO., LTD.
|
Family ID: |
17400750 |
Appl. No.: |
09/963309 |
Filed: |
September 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09963309 |
Sep 26, 2001 |
|
|
|
09374867 |
Aug 16, 1999 |
|
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Current U.S.
Class: |
277/593 |
Current CPC
Class: |
F16J 2015/085 20130101;
F16J 2015/0856 20130101; F16J 15/0825 20130101; F16J 2015/0875
20130101 |
Class at
Publication: |
277/593 |
International
Class: |
F02F 011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 1998 |
JP |
264263/98 |
Claims
What is claimed is:
1. A cylinder head gasket including a first and a second gasket
substrate disposed in overlapping relationship, disposed between a
cylinder head and the cylinder block and each having a combustion
chamber opening formed therein in alignment with a cylinder bore;
characterized in that the first gasket substrate which is disposed
toward the cylinder head is formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head and the second gasket substrate which is disposed
toward the cylinder block is formed with a second inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder block, the first and the second gasket substrate being
disposed in the overlapping relationship to define a clearance
between the first and the second inner projection which project in
opposite directions, the first and the second gasket substrate
being held sandwiched between the cylinder head and the cylinder
block to cause a plastic deformation of the first and the second
inner projection toward the clearance defined therebetween.
2. A cylinder head gasket including a first and a second gasket
substrate disposed in overlapping relationship, held sandwiched
between a cylinder head and a cylinder block and each including a
combustion chamber opening formed therein in alignment with a
cylinder bore; characterized in that the first gasket substrate
which is disposed toward the cylinder head is formed with a first
inner projection surrounding the combustion chamber opening and
projecting toward the cylinder head and including a radially
central part which projects toward the cylinder block, that the
second gasket substrate which is disposed toward the cylinder block
is formed with a second inner projection surrounding the combustion
chamber opening and projecting toward the cylinder block and
including a radially central part which projects toward the
cylinder head, and that the first and the second gasket substrate
are disposed in overlapping relationship so that at least when they
are assembled into an engine, the radially central part of the
first inner projection and the radially central part of the second
inner projection are disposed in close contact with each other
continuously in the circumferential direction.
3. A cylinder head gasket according to claim 1 or 2 further
characterized in that the first gasket substrate is formed with a
first outer projection surrounding the first inner projection and
projecting toward the cylinder head and the second gasket substrate
is formed with a second outer projection surrounding the second
inner projection and projecting toward the cylinder block, the
first and the second gasket substrates being disposed in
overlapping relationship to define a clearance between the first
and the second outer projection which project in opposite
directions.
4. A cylinder head gasket according to claim 3 characterized in
that the first and the second gasket substrate are held sandwiched
between the cylinder head and the cylinder block to cause a plastic
deformation of the first and the second outer projection toward the
clearance defined therebetween.
5. A cylinder head gasket according to claim 1 or 2, further
comprising a first plate and a second plate on the front and the
back side of an assembly of the pair of gasket substrates disposed
in overlapping relationship and each including a combustion chamber
opening formed therein in alignment with the cylinder bore, the
first plate which is disposed in overlapping relationship with the
first gasket substrate being formed with a first full bead
surrounding the combustion chamber opening and projecting toward
the first inner projection, and the second plate which is disposed
in overlapping relationship with the second gasket substrate being
formed with a second full bead surrounding the combustion chamber
opening and projecting toward the second inner projection.
6. A cylinder head gasket according to claim 3, further comprising
a first and a second plate each having a combustion chamber opening
formed therein in alignment with the cylinder bore and disposed on
the front and the rear side of an assembly of the pair of gasket
substrates disposed in overlapping relationship, the first plate
which is disposed in overlapping relationship with the first gasket
substrate being formed with a first full bead surrounding the
combustion chamber opening and projecting toward the first inner
projection and a first half bead disposed outside the first full
bead and projecting toward the first outer projection, the second
plate which is disposed in overlapping relationship with the second
gasket substrate being formed with a second full bead surrounding
the combustion chamber opening and projecting toward the second
inner projection and a second half bead disposed outside the second
full bead and projecting toward the second outer projection.
7. A cylinder head gasket according to claim 3 in which the amount
of the projection of the inner projection is greater than the
amount of projection of the outer projection.
8. A cylinder head gasket according to claim 3 in which the inner
projection has an angle of rise from the associated gasket
substrate which is chosen to be greater than the angle of rise of
the outer projection from the gasket substrate.
9. A cylinder head gasket according to claim 1 or 2 in which a shim
is provided on the inner surface of at least one of the first and
the second inner projection.
10. A cylinder head gasket according to claim 1 or 2 in which a
scarfed layer is formed on the inner surface of at least one of the
first and the second inner projection.
11. A cylinder head gasket according to claim 1 or 2 in which a
resin layer is formed on the inner surface of at least one of the
first and the second inner projection.
12. A cylinder head gasket according to claim 1 or 2 in which the
amount of projection of the first and the second inner projection
is chosen to be small in the vicinity of a clamping bolt which is
used to clamp the cylinder head and the cylinder block, and is
chosen to be greater at a position removed from the clamping
bolt.
13. A cylinder head gasket according to claim 1 or 2 in which the
first and the second inner projection have a width which is wider
in the vicinity of a clamping bolt which is used to clamp the
cylinder head and the cylinder block together, and is chosen to be
narrower at a position removed from the clamping bolt.
14. A cylinder head gasket according to claim 1 or 2 in which the
first and the second inner projection have an angle of rise from
respective associated gasket substrate which is small in the
vicinity of a clamping bolt which is used to clamp the cylinder
head and the cylinder block together, and which is chosen to be
larger at a position removed from the clamping bolt.
15. (New) A cylinder head gasket including first and second gasket
substrates disposed in overlapping relationship, provided between a
cylinder head and a cylinder block and having a combustion chamber
opening formed therein in alignment with a cylinder bore,
characterized in that: the first gasket substrate is disposed
toward the cylinder head and formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head; the second gasket substrate is disposed toward
the cylinder block and formed with a second inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder block; a clearance is defined between the first and
second inner projections; a first plate having a combustion chamber
opening aligned with the cylinder bore is disposed in overlapping
relationship with the first gasket substrate and has a first bead
formed thereon which surrounds the combustion chamber opening and
projects towards the first inner projection; a second plate having
a combustion chamber opening aligned with the cylinder bore is
disposed in overlapping relationship with the second gasket
substrate and has a second bead formed thereon which surrounds the
combustion chamber opening and projects toward the second inner
projection; and the first and second gasket substrates are
compressed between the cylinder head and the cylinder block to
cause plastic deformation of the first and second inner projections
toward the clearance defined therebetween.
16. (New) A cylinder head gasket including first and second gasket
substrates disposed in overlapping relationship, provided between a
cylinder head and a cylinder block and having a combustion chamber
opening formed therein in alignment with a cylinder bore,
characterized in that: the first gasket substrate is disposed
toward the cylinder head and formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head and a first outer projection surrounding the
first inner projection and projecting toward the cylinder head; the
second gasket substrate is disposed toward the cylinder block and
formed with a second inner projection surrounding the combustion
chamber opening and projecting toward the cylinder block and a
second outer projection surrounding the second inner projection and
projecting toward the cylinder block; a clearance is defined
between the first and second inner projections and a clearance is
defined between the first and second outer projections; a first
plate having a combustion chamber opening aligned with the cylinder
bore is disposed in overlapping relationship with the first gasket
substrate and has a first full bead formed thereon which surrounds
the combustion chamber opening and projects toward the first inner
projection and a first half bead formed thereon which is disposed
outside of the first full bead and projects toward the first outer
projection; a second plate having a combustion chamber opening
aligned with the cylinder bore is disposed in overlapping
relationship with the second gasket substrate and has a second full
bead formed thereon which surrounds the combustion chamber opening
and projects toward the second inner projection and a second half
bead formed thereon which is disposed outside of the second full
bead and projects toward the second outer projection; and the first
and second gasket substrates are compressed between the cylinder
head and the cylinder block to cause plastic deformation of the
first and second inner projections toward the clearance defined
between and of the first and second outer projections toward the
clearance defined therebetween.
17. (New) A cylinder head gasket according to claim 16, in which
the amount of projection of the first and second inner projections
is greater than the amount of projection of the first and second
outer projections.
18. (New) A cylinder head gasket according to claim 16, in which
the first and second inner projections have an angle of rise from
the associated gasket substrate greater than the angle of rise of
the first and second outer projections from the gasket
substrate.
19. (New) A cylinder head gasket according to claim 16, in which a
shim is provided on the inner surface of at least one of the first
and the second inner projections.
20. (New) A cylinder head gasket according to claim 16, in which a
scarfed layer is formed on the inner surface of at least one of the
first and the second inner projections.
21. (New) A cylinder head gasket according to claim 16, in which a
resin layer is formed on the inner surface of at least one of the
first and the second inner projections.
22. (New) A cylinder head gasket according to claim 16, in which
the amount of projection of the first and the second inner
projections is smaller in the vicinity of a clamping bolt which is
used to clamp the cylinder head and the cylinder block than at a
position removed from the clamping bolt.
23. (New) A cylinder head gasket according to claim 16, in which
the first and the second inner projection have a width which is
wider in the vicinity of a clamping bolt which is used to clamp the
cylinder head and the cylinder block together than at a position
removed from the clamping bolt.
24. (New) A cylinder head gasket according to claim 16, in which
the first and the second inner projections have an angle of rise
from the respective associated gasket substrate which is smaller in
the vicinity of a clamping bolt which is used to clamp the cylinder
head and the cylinder block together than at a position removed
from the clamping bolt.
25. (New) A cylinder head gasket including first and second gasket
substrates disposed in overlapping relationship, provided between a
cylinder head and a cylinder block and having a combustion chamber
opening formed therein in alignment with a cylinder bore,
characterized in that: the first gasket substrate is disposed
toward the cylinder head and formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head and a first outer projection surrounding the
first inner projection and projecting toward the cylinder head; the
second gasket substrate is disposed toward the cylinder block and
formed with a second inner projection surrounding the combustion
chamber opening and projecting toward the cylinder block and a
second outer projection surrounding the second inner projection and
projecting toward the cylinder block; a clearance is defined
between the first and second inner projections and a clearance is
defined between the first and second outer projections, the sealing
strength of the inner projections being greater than the sealing
strength of the outer projections; a first plate having a
combustion chamber opening aligned with the cylinder bore is
disposed in overlapping relationship with the first gasket
substrate and has a first full bead formed thereon which surrounds
the combustion chamber opening and projects toward the first inner
projection and a first half bead formed thereon which is disposed
outside of the first full bead and projects toward the first outer
projection; a second plate having a combustion chamber opening
aligned with the cylinder bore is disposed in overlapping
relationship with the second gasket substrate and has a second full
bead formed thereon which surrounds the combustion chamber opening
and projects toward the second inner projection and a second half
bead formed thereon which is disposed outside of the second full
bead and projects toward the second outer projection; and the first
and second gasket substrates are compressed between the cylinder
head and the cylinder block to cause plastic deformation of the
first and second inner projections toward the clearance defined
therebetween.
26. (New) A cylinder head gasket according to claim 25, in which
the amount of projection of the first and second inner projections
is greater than the amount of projection of the first and second
outer projections.
27. (New) A cylinder head gasket according to claim 25, in which
the first and second inner projections have an angle of rise from
the associated gasket substrate greater than the angle of rise of
the first and second outer projections from the gasket
substrate.
28. (New) A cylinder head gasket according to claim 25, in which a
shim is provided on the inner surface of at least one of the first
and the second inner projections.
29. (New) A cylinder head gasket according to claim 25, in which a
scarfed layer is formed on the inner surface of at least one of the
first and the second inner projections.
30. (New) A cylinder head gasket according to claim 25, in which a
resin layer is formed on the inner surface of at least one of the
first and the second inner projections.
31. (New) A cylinder head gasket according to claim 25, in which
the amount of projection of the first and the second inner
projections is smaller in the vicinity of a clamping bolt which is
used to clamp the cylinder head and the cylinder block than at a
position removed from the clamping bolt.
32. (New) A cylinder head gasket according to claim 25, in which
the first and the second inner projection have a width which is
wider in the vicinity of a clamping bolt which is used to clamp the
cylinder head and the cylinder block together than at a position
removed from the clamping bolt.
33. (New) A cylinder head gasket according to claim 25, in which
the first and the second inner projections have an angle of rise
from the respective associated gasket substrate which is smaller in
the vicinity of a clamping bolt which is used to clamp the cylinder
head and the cylinder block together than at a position removed
from the clamping bolt.
34. (New) A cylinder head gasket including first and second gasket
substrates disposed in overlapping relationship, provided between a
cylinder head and a cylinder block and having a combustion chamber
opening formed therein in alignment with a cylinder bore,
characterized in that: the first gasket substrate is disposed
toward the cylinder head and formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head and a first outer projection surrounding the
first inner projection and projecting toward the cylinder head; the
second gasket substrate is disposed toward the cylinder block and
formed with a second inner projection surrounding the combustion
chamber opening and projecting toward the cylinder block and a
second outer projection surrounding the second inner projection and
projecting toward the cylinder block; a clearance is defined
between the first and second inner projections and a clearance is
defined between the first and second outer projections; and the
first and second gasket substrates are compressed between the
cylinder head and the cylinder block to cause plastic deformation
of the first and second inner projections toward the clearance
defined therebetween and of the first and second outer projections
toward the clearance defined therebetween.
35. (New) A cylinder head gasket including first and second gasket
substrates disposed in overlapping relationship, provided between a
cylinder head and a cylinder block and having a combustion chamber
opening formed therein in alignment with a cylinder bore,
characterized in that: the first gasket substrate is disposed
toward the cylinder head and formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head and a first outer projection surrounding the
first inner projection and projecting toward the cylinder head; the
second gasket substrate is disposed toward the cylinder block and
formed with a second inner projection surrounding the combustion
chamber opening and projecting toward the cylinder block and a
second outer projection surrounding the second inner projection and
projecting toward the cylinder block; a clearance is defined
between the first and second inner projections and a clearance is
defined between the first and second outer projections; the sealing
strength of the inner projections is greater than the sealing
strength of the outer projections; and the first and second gasket
substrates are compressed between the cylinder head and the
cylinder block to cause plastic deformation of the first and second
inner projections toward the clearance defined therebetween and the
first and second outer projections toward the clearance defined
therebetween.
36. (New) A cylinder head gasket according to claim 35, in which
the amount of projection of the first and second inner projections
is greater than the amount of projection of the first and second
outer projections.
37. (New) A cylinder head gasket according to claim 35, in which
the first and second inner projections have an angle of rise from
the associated gasket substrate greater than the angle of rise of
the first and second outer projections from the gasket
substrate.
38. (New) A cylinder head gasket according to claim 35, in which a
shim is provided on the inner surface of at least one of the first
and the second inner projections.
39. (New) A cylinder head gasket according to claim 35, in which a
scarfed layer is formed on the inner surface of at least one of the
first and the second inner projections.
40. (New) A cylinder head gasket according to claim 35, in which a
resin layer is formed on the inner surface of at least one of the
first and the second inner projections.
41. (New) A cylinder head gasket according to claim 35, in which
the amount of projection of the first and the second inner
projections is smaller in the vicinity of a clamping bolt which is
used to clamp the cylinder head and the cylinder block than at a
position removed from the clamping bolt.
42. (New) A cylinder head gasket according to claim 35, in which
the first and the second inner projection have a width which is
wider in the vicinity of a clamping bolt which is used to clamp the
cylinder head and the cylinder block together than at a position
removed from the clamping bolt.
43. (New) A cylinder head gasket according to claim 35, in which
the first and the second inner projections have an angle of rise
from the respective associated gasket substrate which is smaller in
the vicinity of a clamping bolt which is used to clamp the cylinder
head and the cylinder block together than at a position removed
from the clamping bolt.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a cylinder head gasket used
in an engine.
DESCRIPTION OF THE PRIOR ART
[0002] A cylinder head gasket is known in the art which comprises a
first and a second gasket plate disposed in overlapping
relationship, held sandwiched between a cylinder head and a
cylinder block and each having a combustion chamber opening formed
therein in alignment with a cylinder bore.
[0003] In a cylinder head gasket of the type described, as an
explosion pressure of an engine increases, a gas in a combustion
chamber may blow through a clearance between the cylinder head
gasket and the cylinder head, between the cylinder head gasket and
the cylinder block or between a first and a second gasket substrate
which form together the cylinder head gasket.
[0004] For purpose of reducing the weight of an engine, a cylinder
block which is made from aluminium is recently employed, with a
cast iron liner being usually provided on the cylinder bore in
order to secure an abrasion resistance thereof. Such a liner may be
secured in place by a press fit or by a casting technique. In the
press fit technique, the end of the liner is formed with a flange,
which is disposed in abutment against an offset step formed on the
block so that the both parts may be positioned and the liner can be
secured by a press fit in the cylinder block.
[0005] For a multi-cylinder engine including a plurality of press
fit liners, if each liner is mounted on the cylinder block in an
even manner, there often results a delicate difference in the
amount of projection above the surface of the cylinder block from
liner to liner.
[0006] Accordingly, when the cylinder head gasket is interposed
between the cylinder head and the cylinder block, which are then
clamped together by clamping bolts, a failure of a bead on the
cylinder head gasket may occur in a region thereof which is
contacted by a liner which projects above the surface of the
cylinder block to cause an excessively high pressure of contact or
the offset step on the cylinder block which is abutted by the liner
flange may be deformed to cause a blow-through of a gas in the
combustion chamber. The likelihood of causing a blow-through of a
gas in the combustion chamber also exists in a region of the
cylinder head gasket which is contacted by a liner which remains
depressed below the surface of the cylinder block to present an
excessively low pressure of contact.
[0007] When the cylinder head and the cylinder block are clamped
together by the clamping bolts, the surface pressure is high in a
region located adjacent to one of the bolts while the surface
pressure decreases with a distance from the bolts, causing a
degradation in the sealing performance of some engines at a
distance from the clamping bolts, again giving rise to the
likelihood of producing a blow-through of a gas in the combustion
chamber.
SUMMARY OF THE INVENTION
[0008] The present invention provides a cylinder head gasket
capable of preventing the occurrence of a blow-through of a
combustion gas more effectively.
[0009] The invention also provides a cylinder head gasket which
allows the occurrence of a blow-through of a combustion gas to be
prevented by enabling a surface pressure which is as even as
possible to be achieved when a cylinder head and a cylinder block
are clamped together by clamping bolts.
[0010] Specifically, according to a first aspect of the invention,
there is provided a cylinder head gasket including a first and a
second gasket substrate disposed in overlapping relationship, held
sandwiched between a cylinder head and a cylinder block and each
having a combustion chamber opening formed therein in alignment
with a cylinder bore, the first gasket substrate being disposed
toward the cylinder head and formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head and the second gasket substrate being disposed
toward the cylinder block and formed with a second inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder block, the first and the second gasket substrate being
disposed in overlapping relationship to define a clearance between
the first and the second inner projection which project in opposite
direction from each other, the first and the second gasket
substrate being held sandwiched between the cylinder head and the
cylinder block in a manner to cause a plastic deformation of the
first and the second inner projection toward the clearance defined
therebetween.
[0011] According to a second aspect of the invention, a cylinder
head gasket of a conventional type as mentioned above is
characterized in that the first gasket substrate which is disposed
toward the cylinder head is formed with a first inner projection
surrounding the combustion chamber opening and projecting toward
the cylinder head and including a radially central part which
projects toward the cylinder block, that the second gasket
substrate which is disposed toward the cylinder block is formed
with a second inner projection surrounding the combustion chamber
opening and projecting toward the cylinder block and including a
radially central part which projects toward the cylinder head, and
that the first and the second gasket substrate are disposed in
overlapping relationship such that at least when they are assembled
into an engine, the radially central part the first inner
projection and the radially central part of the second inner
projection are disposed to be in close contact with each other
continuously in the circumferential direction.
[0012] Accordingly, according to the first aspect of the invention,
when the cylinder head gasket is held sandwiched between the
cylinder head and the cylinder block, which are clamped together by
clamping bolts, the first inner projection of the first gasket
substrate and the second inner projection of the second gasket
substrate undergo a plastic deformation in a direction toward the
clearance defined therebetween.
[0013] If there is a delicate difference in the amount of
projection above the surface pressure of the cylinder block from
liner to liner, or if the surface pressure is high in a region
adjacent to clamping bolts while it is low away therefrom, the both
inner projections will undergo a magnitude of a plastic deformation
which varies in accordance with the surface pressure, with
consequence that there is secured an even pressure of contact,
enabling a local blow-through to be prevented.
[0014] According to the second aspect of the invention, the
radially central part of the first inner projection which projects
toward the cylinder block and the radially central part of the
second inner projection which projects toward the cylinder head are
disposed to be in close contact with each other, continuously in
the circumferential direction, and accordingly, the pressure of any
combustion gas which tends to blow through a clearance therebetween
urges the first inner projection toward the cylinder head and urges
the second inner projection toward the cylinder block. As the first
inner projection is urged against the cylinder head by the gas
pressure, the sealing performance thereof is improved. Similarly,
as the second inner projection is urged against the cylinder block
by the gas pressure, the sealing performance thereof is improved.
In addition, when the first inner projection is urged against the
cylinder head and the second inner projection is urged against the
cylinder block, reactions from these urging effects drive the
radially central parts of the first and the second inner projection
into more tight contact with each other, thus improving the sealing
performance in such area.
[0015] Above and other objects, features and advantages of the
invention will become apparent from the following description of
several embodiments thereof with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a plan view of a first embodiment of the
invention;
[0017] FIG. 2 is a cross section taken along the line II-II shown
in FIG. 1;
[0018] FIG. 3 is a cross section taken along the line III-III shown
in FIG. 1;
[0019] FIG. 4 is an enlarged cross section of part shown in FIG.
3;
[0020] FIG. 5 is an enlarged section illustrating a plastic
deformation of an increased magnitude of a first inner projection
2A and a second inner projection 3A;
[0021] FIG. 6 is an enlarged cross section illustrating a plastic
deformation of a reduced magnitude of the first inner projection 2A
and the second inner projection 3A;
[0022] FIG. 7 is a cross section of a second embodiment of the
invention;
[0023] FIG. 8 is a cross section of a third embodiment of the
invention;
[0024] FIG. 9 is a cross section of a fourth embodiment of the
invention;
[0025] FIG. 10 is a cross section of a fifth embodiment of the
invention; and
[0026] FIG. 11 is a cross section taken at a different position
from FIG. 10.
DETAIL DESCRIPTION OF THE EMBODIMENTS
[0027] Embodiments in which the present invention is applied to a
cylinder head gasket for four cylinder tandem engine will be
described.
[0028] Referring to FIGS. 1 to 3, a cylinder head gasket I
comprises a first gasket substrate 2 and a second gasket substrate
3 of a relatively increased thickness which are disposed in
overlapping relationship. A first plate 4 and a second plate 5 of a
relatively reduced thickness are disposed in overlapping
relationship with the front and the back surface of the assembly of
gasket substrates. As shown in FIG. 1, four combustion chamber
openings 10 are formed through the gasket substrates 2,3 and the
plates 4, 5 in alignment with a cylinder bore 9 of an engine as are
bolt holes 11 for passing clamping bolts, not shown, and water
holes 12 through which a cooling water is passed. The gasket
substrates 2, 3 and the plates 4, 5 are integrally fastened
together by means such as lancelock.
[0029] As is well known in the art, the cylinder head gasket 1 is
interposed between a cylinder head (not shown), and a cylinder
block 13 of an engine, which are integrally fastened together by
clamping bolts mentioned above, whereby the gasket 1 is held
sandwiched therebetween to provide a seal therebetween.
[0030] The upper or the first gasket substrate 2, which is disposed
toward a cylinder head, not shown, is formed with a first inner
position 2A surrounding the combustion chamber opening 10 and
projecting toward the cylinder head while the lower or the second
gasket substrate 3, which is disposed toward the cylinder block 13,
is formed with a second inner projection 3A surrounding the
combustion chamber opening 10 and projecting toward the cylinder
block 13.
[0031] The first and the second inner projection 2A, 3A are formed
symmetrically to each other with respect to a mating surface
between the substrates 2, 3, and when both gasket substrate 2, 3
are disposed in an overlapping relationship, a clearance or an air
gap 14 (see FIG. 4) is defined between the first and the second
inner projections 2A, 3A which project in opposite directions.
[0032] In addition, the first gasket substrate 3 is formed with a
first outer projection 2B surrounding the first inner projection 2A
and projecting toward the cylinder head, and the second gasket
substrate 3 is formed with a second outer projection 3B surrounding
the second inner projection 3A and projecting toward the cylinder
block 13.
[0033] The first and the second outer projection 2B, 3B are also
formed symmetrically to each other with respect to a mating surface
between the both gasket substrates 2, 3, whereby when the both
gasket substrates 2, 3 are disposed in overlapping relationship, a
clearance or an air gap 15 (see FIG. 4) can be defined between the
first and the second outer projection 2B, 3B which project in
opposite directions.
[0034] The opposing surfaces of the first and the second inner
projection 2A, 3A are formed as annular grooves which surround the
combustion chamber opening 10 and which define the air gap 14. As
shown to an enlarged scale in FIG. 4, each of these annular grooves
is formed with a sidewall 2Aa, or 3Aa which is located on the inner
periphery or toward the combustion chamber opening 10 and another
sidewall 2Ab or 3Ab on the outer periphery.
[0035] By contrast, the opposing surfaces of the first and the
second outer projection 2B, 3B are not formed as annular grooves
but are formed as recesses. In other words, the both outer
projections 2B, 3B are formed with sidewalls 2Ba, 3Ba toward the
combustion chamber opening 10 so as to surround it, but are not
provided with sidewalls on the other side.
[0036] As a consequence, as considered in a region located between
a pair of adjacent combustion chamber openings 10, the air gap 15
will be formed between the sidewalls 2Ba, 3Ba which are adjacent to
each other, as shown in FIG. 3, but the inner surfaces of the both
outer projections 2B, 3B which are formed as recesses will contact
each other in regions other than the region between the pair of
adjacent combustion chamber openings 10. Thus it will be seen that
the air gap 15 is formed in an extent lying between the sidewalls
2Ba, 3Ba to an area of contact between the both recessed
surfaces.
[0037] On the other hand, the first plate 4 is formed with a first
full bead 4A which surrounds the combustion chamber opening 10 and
a first half bead 4B which surrounds the first full bead 4A, the
first full bead 4A being formed to project toward the first inner
projection 2A of the first gasket substrate 2 and the first half
bead 4B being formed to project toward the first outer projection
2B of the first gasket substrate 2.
[0038] Similarly, the second plate 5 is formed with a second full
bead 5A which surrounds the combustion chamber opening 10 and a
second half bead 5B which surrounds the second full bead 5A, the
second full bead 5A being formed to project toward the second inner
projection 3A of the second gasket substrate 3 and the second half
bead 5B being formed to project toward the second outer projection
3B of the second gasket substrate 3. It will be noted that the full
beads 4A, 5A and the half beads 4B, 5B are formed to define a
surface symmetry.
[0039] In the embodiment shown, the cylinder block 13 is provided
with a liner 16, as shown in FIGS. 2 and 3, and the liner 16 is
formed with a flange 16A at its top end which extends radially
outward. The liner 16 is secured as a press fit in the cylinder
block 13, and the bottom surface of the flange 16A is disposed in
abutment against the upper surface of an offset step 13A formed in
the cylinder block 13, thereby positioning the liner 16 on the
cylinder block 13.
[0040] The first inner projection 2A of the first gasket substrate
2, the second inner projection 3A of the second gasket substrate 3,
the first full bead 4A of the first plate 4 and the second full
bead 5A of the second plate 5 are placed as an overlapping assembly
on top of the flange 16A of the liner 16.
[0041] On the other hand, the first outer projection 2B of the
first gasket substrate 3, the second outer projection 3B of the
second gasket substrate 3, the first half bead 4B of the first
plate 4 and the second half bead 5B of the second plate 5 are
placed, as an overlapping assembly, on top of the cylinder block 13
on the outer side of the flange 16A. Under this condition, the
cylinder head gasket 1 is held between the cylinder head and the
cylinder block 13 by the clamping bolts mentioned above.
[0042] With the described construction, the cylinder head gasket 1
is interposed between the cylinder head and the cylinder block 13
of an engine, and is sealed therebetween by integrally fastening
the cylinder head and the cylinder block 13 by clamping bolts. At
this time, the first inner projection 2A of the first gasket plate
2 and the second inner projection 3A of the second gasket plate 3
undergo a plastic deformation toward the air gap 14 under the
influence of the surface pressure, and the first outer projection
2B of the first gasket substrate 2 and the second outer projection
3B of the second gasket substrate 3 also undergo a plastic
deformation toward the air gap 15.
[0043] In the event the liner 16 projects slightly above the
cylinder block 13 to increase the surface pressure in such region,
the first inner projection 2A and the second inner projection 3A
will experience an increased magnitude of plastic deformation
toward the air gap 14 under the influence of the surface pressure,
as illustrated in FIG. 5. By contrast, when the liner 16 is
slightly recessed from the cylinder block 13 to reduce the surface
pressure in such area, the first inner projection 2A and the second
inner projection 3A will experience a slight magnitude of plastic
deformation toward the air gap 14 under the influence of the
surface pressure, as illustrated in FIG. 6. As a consequence, a
surface pressure which is as even as possible can be obtained over
the entire region of the four cylinder engine, thus preventing the
occurrence of a blow-through of a combustion gas in a region of a
reduced surface pressure.
[0044] It will be noted that considering a single liner 16, the
surface pressure will be high at a position adjacent to the bolt
hole 11, but will be low at a position which is removed from the
bolt hole 11. However, the first inner projection 2A and the second
inner projection 3A experience a magnitude of a plastic deformation
in the circumferential direction of the combustion chamber opening
10 which varies depending on the magnitude of the surface pressure,
whereby it is possible to maintain as even a surface pressure as
possible in the circumferential direction of the combustion chamber
opening 10.
[0045] At a position where the surface pressure is high, the first
inner projection 2A and the second inner projection 3A will
experience an increased magnitude of plastic deformation toward the
air gap 14 under the influence of the surface pressure, as
illustrated in FIG. 5, but it will be noted that regions close to
the sidewalls 2Aa, 2Ab, 3Aa and 3Ab of the respective projections
2A, 3A are less susceptible to the plastic deformation than the
central regions, whereby these sidewall regions act as bead stop,
thus preventing the respective full beads 4A, 5A from being
excessively compressed to be damaged. The same is true with the
first outer projection 2B, the second outer projection 3B, the
first half bead 4B and the second half bead 5B.
[0046] FIG. 7 shows a second embodiment of the invention in which
the inner projections 2A, 3A are left free without placing them in
close contact toward the combustion chamber opening 10 while the
outer projections 2B, 3B are formed with sidewalls on both the
inner and the outer periphery so that the outer projections are
disposed in close contact with each other on the outside of the
both sidewalls.
[0047] In addition, the full beads 4A, 5A and the half beads 4B, 5B
are interchanged in position as compared with the first embodiment,
with the half beads 4B, 5B being disposed in overlapping
relationship with the corresponding inner projections 2A, 3A and
the full beads 4A, 5A being disposed in overlapping relationship
with the outer projections 2B, 3B.
[0048] It is also to be noted that the full beads 4A, 5A and the
outer projections 2B, 3B are disposed nearer the combustion chamber
opening 10 than in the first embodiment, whereby the inner
periphery of the outer projections 2B, 3B is disposed in
overlapping relationship with the liner 16 and the full beads 4A,
5A are disposed across the liner 16 and the cylinder block 13.
[0049] FIG. 8 shows a third embodiment of the invention in which
the first outer projection 2B of the first gasket substrate 3, the
second outer projection 3B of the second gasket substrate 3, the
first half bead 4B of the first plate 4 and second half bead 5B of
the second plate 5 shown in the first embodiment are omitted.
[0050] On the other hand, a shim 21 is disposed within the air gap
14 in order to improve the sealing performance. It is preferred
that the shim 21 be secured to at least one of the gasket substrate
2 and 3 for handling reason, and may be secured to the second
gasket substrate 3 by a spot welding along the center line of the
shim 21. The shim 21 has a thickness which is preferably equal to
or less than one-half the height of the air gap 14 defined between
the inner projections 2A and 3A.
[0051] As an alternative to providing the shim 21, a resin layer
may be provided by a resin sheet which is adhesively bonded or by
providing a resin coating. Preferably, the resin layer comprises
polyamide or polyamideimide which exhibits high heat resistance,
and which may be blended with a filler such as a graphite, carbon
fiber, glass fiber or clay in order to improve the strength, the
heat resistance and/or adhesion.
[0052] In place of the shim 21 or a resin layer, a scarfed layer
may be provided. It should be understood that any one of shim 21, a
resin layer or a scarfed layer may also be provided in the first or
second embodiment.
[0053] FIG. 9 shows a fourth embodiment of the invention, which is
fundamentally constructed in the similar manner as the first
embodiment. However, in the present embodiment, in order to provide
an optimized sealing performance, the strengths of the inner
projections 2A, 3A disposed toward the full beads 4A, 5A are chosen
to be greater than the strengths of the outer projections 2B, 3B
disposed toward the half beads 4B, 5B.
[0054] More specifically, the amount of projection hf of each of
the inner projections 2A, 3A is chosen to be larger than the amount
of projection hh of the outer projections 2B, 3B. In addition or
alternatively, an angle of rise .theta. f of each sidewall of the
inner projections 2A, 3A may be chosen to be greater than an angle
of rise .theta. h of each sidewall of the outer projections 2B,
3B.
[0055] When the strengths of the inner projections 2A, 3A disposed
toward the full beads 4A, 5A are chosen to be greater than the
strengths of the outer projections 2B, 3B disposed toward the half
beads 4B, 5B, the surface pressure which is generated in the region
of the full beads 4A, 5A during the clamping operation becomes
greater than the surface pressure generated in the region of the
half beads 4B, 5B, thus providing a more optimized sealing
performance.
[0056] More specifically, a sealing force which is generally
required for a half bead is on the order of 0.3 to 0.4 MPa, which
is necessary in order to prevent an ingress of cooling water onto
the end face of the liner and to prevent a gas which may leak from
the full bead from becoming mixed into the cooling water. On the
other hand, a sealing force which is required for a full bead is on
the order of 6 to 9 MPa, which is necessary to seal against the
explosion pressure of an engine. According to the type of the
engines, higher sealing force for full bead will be required. Thus,
the sealing force required of the full bead is greater than the
sealing force applied to the half bead.
[0057] A clearance between the cylinder head and the cylinder block
is designed to be narrow in a peripheral region and wider in a
region adjacent to the bore. Accordingly, if the inner projections
2A, 3A has an offset height which is chosen to be the same as that
the outer projections 2B, 3B, the surface pressure in the region of
the outer projections 2B, 3B will be relatively higher, which is
undesirable.
[0058] In addition, if the liner 16 lies depressed below the
surface of the cylinder block 13, the surface pressure in the
region of the outer projections 2B, 3B will be relatively higher,
which is also undesirable. However, if the liner 16 projects above
the surface of the cylinder block 13, the surface pressure in the
region of the inner projections 2A, 3A will be relatively higher,
which is desirable.
[0059] From these considerations, the sealing force of the outer
projections 2B, 3B may be chosen such that the half beads are
capable of sealing the cooling water when the liner 16 projects
above the surface of the cylinder block 13.
[0060] In each embodiment described above, the first inner
projection 2A and the second inner projection 3A have an identical
cross section circumferentially of the combustion chamber opening
10, but their shapes may be changed depending on the location of
the bolt holes 11 associated with clamping bolts so that a more
even surface pressure prevails adjacent to and removed from the
bolt holes 11.
[0061] More specifically, in the vicinity of the bolt hole 11, for
example, in a region located within about 20.degree. to 30.degree.
centered about a line joining the center of the combustion chamber
opening 10 and the center of the bolt hole 11, the amount of
projection h of each of the inner projections 2A, 3A, as
illustrated in FIG. 4, may be reduced, its radial width w increased
or an angle of rise .theta. of each sidewall reduced in comparison
to a corresponding quantity at a position removed from the bolt
hole 11. Obviously, these choices may be used in combination.
Alternatively, rather than providing a surface pressure which is as
even as possible in the circumferential direction, a design may be
employed which provides a slightly higher surface pressure in the
region adjacent to the combustion chamber opening 10.
[0062] FIG. 10 shows a fifth embodiment of the invention, which is
fundamentally constructed in the similar manner as the first
embodiment.
[0063] In the present embodiment, an upper or a first gasket
substrate 102 which is disposed toward a cylinder head, not shown,
is formed with a first inner projection 102A surrounding a
combustion chamber opening 110 and projecting toward the cylinder
head and including a radially central part 102a projects downward
or toward a cylinder block, not shown, presenting an arcuate
configuration in section. On the other hand, a lower or a second
gasket substrate 103 disposed toward the cylinder block is formed
with a second inner projection 103A surrounding the combustion
chamber opening 110 and projecting downward and including a
radially central part 103a which is arcuate in section and
projecting upward or toward the cylinder block.
[0064] The first inner projection 102A and the second inner
projection 103A are formed symmetrically to each other with respect
to a mating surface between the both gasket substrates 102, 103,
and when the both gasket substrates 102, 103, are disposed in
overlapping relationship, the radially central part 102a of the
first inner projection 102A and the radially central part 103a of
the second inner projection 103A are disposed to be in close
contact with each other continuously in the circumferential
direction.
[0065] The first gasket substrate 103 is also formed with a first
outer projection 102B surrounding the first inner projection 102A
and projecting upward, and the second gasket substrate 103 is
formed with a second outer projection 103B surrounding the second
inner projection 103A and projecting downward.
[0066] The first outer projection 102B and the second outer
projection 103B are also formed symmetrically to each other with
respect to a mating surface between the both gasket substrates 102,
103, and when both gasket substrates 102, 103 are disposed in
overlapping relationship, the first outer projection 102B and the
second outer projection 103B which project in opposite directions
are spaced from each other on their side located adjacent to the
combustion chamber opening 110, but are disposed to be in close
contact with each other at a position which is by a given distance
removed on the opposite side or away from the combustion chamber
opening 110.
[0067] It is to be noted that the first inner projection 102A and
the second inner projection 103A have a height and an angle of rise
along its inner and outer peripheries which vary in the
circumferential direction. Specifically, FIG. 10 shows a cross
section at an intermediate position between bolt holes through
which the clamping bolts are passed (see the location indicated by
the line III-III shown in FIG. 1), and it will be seen that at this
position, the first inner projection 102A and the second inner
projection 103A have an increased height h1 along the inner and
outer peripheries and have an increased angle of rise .theta.1 from
the body of the gasket substrates 102, 103. By contrast, FIG. 11
shows a corresponding cross section taken at a position which is
close to a bolt hole through which a clamping bolt is passed. At
this position, the first projection 102A and the second inner
projection 103A have a reduced height h2 and a reduced angle of
rise .theta.2 along the inner and outer peripheries. The heights
h1, h2 and angles .theta.1, .theta.2, prevail over a given extent
centered about the intermediate position between the bolt holes and
the position close to the bolt hole, with both the height and the
angle smoothly changing from one of the values to the other.
[0068] A first plate 104 is formed with a first full bead 104A
which surrounds the combustion chamber opening 110 and a first half
bead 104B which surrounds the first full bead 104A, the first full
bead 104A being formed to project toward the first inner projection
102A of the first gasket substrate 102 and the first half bead 104B
being formed to project toward the first outer projection 102B of
the first gasket substrate 102.
[0069] Similarly, a second plate 105 is formed with a second full
bead 105A which surrounds the combustion chamber opening 110 and a
second half bead 105B which surrounds the second full bead 105A,
the second full bead 105A being formed to project toward the second
inner projection 103A of the second gasket substrate 103 and the
second half bead 105B being formed to project toward the second
outer projection 103B of the second gasket substrate 103. It will
be noted that these full beads 104A, 105A and the half beads 104B,
105B are formed to provide a surface symmetry.
[0070] With the described construction, the cylinder head gasket
101 is interposed between a cylinder head and a cylinder block of
an engine, and is sealed therebetween by integrally fastening the
cylinder head and the cylinder block by using clamping bolts.
[0071] As viewed in the circumferential direction of the combustion
chamber opening 110, the surface pressure at a position close to
the clamping bolt is increased and is reduced at a position removed
therefrom. However, because the first inner projection 102A and the
second inner projection 103A have a circumferentially varying
height, as indicated at h1 and h2, and also a circumferentially
varying angle of rise, as indicated at .theta.1, .theta.2, along
the inner and outer peripheries thereof, the surface pressure
applied to the first inner projection 102A and the second inner
projection 103A can be made as even as possible when viewed in the
circumferential direction of the combustion chamber opening
110.
[0072] When the engine is in operation, any combustion gas which
tends to blow through a clearance between the first inner
projection 102A and the second inner projection 103A to the
exterior exhibits a pressure which urges the first inner projection
102A toward the cylinder head and which simultaneously urges the
second inner projection 103A toward the cylinder block. The surface
pressure acting between the first inner projection and the cylinder
head then increases, thus improving the sealing performance of such
region. Similarly, the surface pressure acting between the second
inner projection and the cylinder block increases, also improving
the sealing performance in such region. When the first inner
projection 102A is pressed against the cylinder head and the second
inner projection 103A is pressed against the cylinder block,
reactions from these pressures force the radially center part 102a
of the first inner projection 102A and the radially central part
103a of the second inner projection 103A into a more tight contact
with each other, thus improving the sealing performance in such
region.
[0073] In this manner, the first gasket substrate 102 and the
second gasket substrate 103 are pressed against each other at the
same time as they are pressed against the cylinder head and the
cylinder block, respectively, under the pressure of the combustion
gas, thus preventing a blow-through of the combustion gas more
effectively than in the prior art.
[0074] It is to be noted that rather than providing a surface
pressure which is made as even as possible in the circumferential
direction, a slightly higher surface pressure may be established in
the region adjacent to the combustion chamber opening 110.
[0075] A number of modifications which are mentioned above may also
be applied to the present embodiment.
[0076] While the invention has been shown and described above in
connection with several embodiments thereof, it should be
understood that a number of changes, modifications and
substitutions therein are possible by one skilled in the art from
the above disclosure without departing from the spirit and the
scope of the invention defined by the appended claims.
* * * * *